Publications by authors named "Hoseong Hwang"

2 Publications

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Natural photosensitizers from Tripterygium wilfordii and their antimicrobial photodynamic therapeutic effects in a Caenorhabditis elegans model.

J Photochem Photobiol B 2021 May 29;218:112184. Epub 2021 Mar 29.

Natural Product Informatics Research Center, Gangneung Institute of Natural Products, Korea Institute of Science and Technology, Gangwon-do 25451, Republic of Korea; Division of Bio-Medical Science & Technology, KIST School, University of Science and Technology (UST), Gangneung, Gangwon-do 25451, Republic of Korea. Electronic address:

Tripterygium wilfordii Hook. f. is a traditional medicinal plant and has long been used in East Asia to treat many diseases. However, the extract and active components have never been investigated as potential photosensitizers for photodynamic treatment to kill pathogenic microorganisms. Here, the antimicrobial photodynamic treatment (APDT) effects of the extract, fractions, and compounds of T. wilfordii were evaluated in vitro and in vivo. Ethanolic extract (TWE) and the photosensitizer-enriched fraction (TW-F5) were prepared from dried T. wilfordii. Six active compounds were isolated from TW-F5 by semipreparative high-performance liquid chromatography, and their chemical structures were characterized through spectroscopic and spectrometric analysis. The singlet oxygen from extracts, fractions, and compounds was measured by using the imidazole-N,N-dimethyl-4-nitrosoaniline method. These extracts, fractions, and compounds were used as photosensitizers for the inactivation of bacteria and fungi by red light at 660 nm. The in vitro APDT effects were also evaluated in the model animal Caenorhabditis elegans. APDT with TWE showed effective antimicrobial activity against Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), and Candida albicans. TW-F5, consisting of six pheophorbide compounds, also showed strong APDT activity. The photosensitizers were taken up into the bacterial cells and induced intracellular ROS production by APDT. TWE and TW-F5 also induced a strong APDT effect in vitro against skin pathogens, including Staphylococcus epidermidis and Streptococcus pyogenes. We evaluated the APDT effects of TWE and TW-F5 in C. elegans infected with various pathogens and found that PDT effectively controlled pathogenic bacteria without strong side effects. APDT reversed the growth retardation of worms induced by pathogen infection and decreased the viable pathogenic bacterial numbers associated with C. elegans. Finally, APDT with TWE increased the survivability of C. elegans infected with S. pyogenes. In summary, TWE and TW-F5 were found to be effective antimicrobial photosensitizers in PDT.
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http://dx.doi.org/10.1016/j.jphotobiol.2021.112184DOI Listing
May 2021

Mussel-Inspired Defect Engineering of Graphene Liquid Crystalline Fibers for Synergistic Enhancement of Mechanical Strength and Electrical Conductivity.

Adv Mater 2018 Aug 8:e1803267. Epub 2018 Aug 8.

National Creative Research Initiative Center for Multi-Dimensional Directed Nanoscale Assembly, Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea.

Inspired by mussel adhesive polydopamine (PDA), effective reinforcement of graphene-based liquid crystalline fibers to attain high mechanical and electrical properties simultaneously is presented. The two-step defect engineering, relying on bioinspired surface polymerization and subsequent solution infiltration of PDA, addresses the intrinsic limitation of graphene fibers arising from the folding and wrinkling of graphene layers during the fiber-spinning process. For a clear understanding of the mechanism of PDA-induced defect engineering, interfacial adhesion between graphene oxide sheets is straightforwardly analyzed by the atomic force microscopy pull-off test. Subsequently, PDA could be converted into an N-doped graphitic layer within the fiber structure by a mild thermal treatment such that mechanically strong fibers could be obtained without sacrificing electrical conductivity. Bioinspired graphene-based fiber holds great promise for a wide range of applications, including flexible electronics, multifunctional textiles, and wearable sensors.
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http://dx.doi.org/10.1002/adma.201803267DOI Listing
August 2018